Return to the Report homepage, where you will find an upload button by your owned twitter profile.

Have analytics.twitter.com loaded up in a separate browser tab/window and make sure you are logged into the account. 

Here, you'll need to go to the 'Tweets' tab and select your date range before selecting the 'Export data' button in the top left hand corner of this page. 

Once you've downloaded the CSV file, you'll need to go back to your Locowise report screen and upload it using the upload button. 

Once complete, you will gain full and accurate visibility of your tweet-level impression data.